The present invention relates to a total or partial ureteral prosthesis. Known ureteral prostheses suffer from various difficulties and complications in their use. The difficulties encountered include the following: the need to adapt the prosthesis to the patient's size involves risks of distortion and consequent stasis, and risks of migration of the prosthesis; positioning of existing ureteral prostheses frequently causes residual hydronephroses, which are the result of persistent stasis; the positioning of existing ureteral prostheses also frequently involves urinary infections and lithiases which can complicate these infections.
The difficulties encountered are due to several factors and particularly to the more or less substantial rigidity of the prosthesis, to its shape, to the cross-section of its aperture, the quality of its internal surface and to the presence or absence of an anti-reflux system.
Known ureteral prostheses which attempt to solve the above difficulties include "straight" prostheses made of "Scurasil" (French Trade mark registered by RHONE POULENC, designating a dimethylpolysiloxane), and including muffs made of "Rhodergon" (Registered French Trademark), a velvet cloth of polyester (see Sausse et al, U.S.P at. No. 3,783,454, col. 2, lines 44-51) to anastomose the prosthesis to the surrounding tissue.
Although there is a description in existence of these straight ureteral prostheses made of "Scurasil" which states that they are made with an anti-reflux valve at their vesical extremity (cf.BRITISH JOURNAL OF UROLOGY (1974) 46,415-424), nevertheless the straight ureteral prostheses made of "Scurasil" and perfected by RHONE POULENC from 1967 onwards are not provided with anti-reflux valves, due to the need to provide for an internal surface of high quality which led the RHONE POULENC Company to perfect a process of lacquering the internal side walls of the prostheses as well as the external ones--at least partially--with the aid of a vulcanized silicone elastomer smooth coating. Since, however, this lacquering process is very difficult to apply to anti-reflux valves, it has not been found practical to produce such prostheses as proposed in conformity with the foregoing publication, which have both a high quality internal surface which is obtained by lacquering and an anti-reflux valve.
this is made particularly clear in the literature distributed by the RHONE POULENC Company concerning its "Scurasil" ureteral-vesical prostheses.
Since the above ureteral prosthesis is of a kind which does not solve the above problems in their entirety, by reason of its insufficient flexibility or of its nonextensibility, another ureteral prosthesis has also been proposed by the same Company, which prosthesis, also made of "Scurasil", is made up of a flexible, extensible helical tube which is, therefore, of variable length according to the size which it is wished to give to the prosthesis. Such a prosthesis also solves the problem of adaptation of the prosthesis to the size of the patient, as well as the problem of distortion.
However, these helical prostheses; like "straight" ureteral prostheses, do not include any anti-reflux valve and do not have a peristaltic mechanism. The absence of a peristaltic mechanism from the prostheses constitutes an obstacle to the outflow of urine, so that these prostheses are also unable to solve all the difficulties mentioned above.
Although the ureteral prostheses which have just been described are clearly superior to the ureteral prostheses which were proposed still earlier (which comprised essentially rigid tubes or reinforced tubes) they do have an undesirable resistance to outflow which results in their being unable to prevent the risks of consequential stasis as well as urinary infections and lithiases.
In the above-mentioned publication it was also proposed, in order to ensure a suitable peristaltic mechanism favoring the outflow of urine, to position a centrifugal pump between the kidney and the bladder, the aforesaid pump being driven by a direct current electric motor, the intermittent operation of which would be controlled by an impulse generator.
Although such a centrifugal pump system provides the desired peristaltic mechanism, nevertheless the implantation of the pump and of the associated electrical and electronic systems for controlling it, present numerous disadvantages. Numbered among these must be the complication of surgical intervention for the purposes of implantation, the relatively unsatisfactory compatibility of the equipment and the formation of encrustations (notably crystallized mineral salts) which produce lithiases, so that the implantation of these pumps has not been developed because their disadvantages outweigh their advantages.
It has also been proposed to assist the outflow of urine in ureteral prostheses with the aid of a tubular diaphragm pump which is inserted into the ureteral prosthesis and which is associated with a hydraulic system implanted in a pleural cul-de-sac and which controls displacement of the aforesaid pump under the influence of the respiratory movement of the patient.
This system is however of great complexity and is difficult to construct as well as being difficult to implant because of the complications of the necessary surgical intervention required for implantation and the consequences arising from such an implantation, so that this system has not been retained in practice for the purposes of solving the difficulties posed by ureteral prosthesis.